Environmental stress during the last trimester of gestation in pregnant cows and its effect on offspring growth performance and response to glucose and adrenocorticotropic hormone.

Winter and spring precipitation are predicted to increase in the Midwest region of the United States, causing muddy conditions. In a previous experiment, Angus cows (8 per treatment) were paired based on initial body weight (BW) and one cow from each pair was randomly allocated to either the mud or control treatment. Though cows consumed the same amount of dry matter, cows in the mud treatment weighed 37.4 kg less than cows in the control treatment by day 269 of gestation. The objective of this experiment was to evaluate developmental programming effects of steers born to cows in the mud treatment (MUD; n = 7) or the control treatment (CON; n = 6). Steers were weighed at birth and then weekly from approximately 56 d of age until weaning and were subjected to a glucose tolerance test (GTT) and adrenocorticotropic hormone (ACTH) challenge after weaning. Steers were then placed in the feedlot for an 84-d growing phase and were weighed weekly and 12th rib back fat (BF) and ribeye area (REA) were imaged every 28 d using ultrasonography. Data were analyzed as a randomized complete block design with repeated measurements when appropriate (SAS 9.4). Although there was a 37.4 kg decrease in BW of cows by the end of gestation, there was no evidence of a pen treatment effect on calf birth weight (P = 0.60) or weaning weight (P = 0.99). Additionally, there was no evidence of a pen treatment × day effect for steer BW from birth to weaning (P = 0.67) or growing phase BW (P = 0.60). There was evidence of a treatment × day of growing phase effect (P = 0.02) for BF, such that CON steers had greater BF on day 28 of the growing phase; however, there was no evidence of a treatment × day effect for REA (P = 0.20). Furthermore, there was no evidence of a pen treatment effect for the growing phase average daily gain (P = 0.74), dry matter intake (P = 0.65), gain:feed (P = 0.48), plasma glucose concentration (P = 0.67) or plasma insulin concentration (P = 0.61) in response to the GTT, or plasma cortisol concentration in response to the ACTH challenge (P = 0.51). These results indicate that while mud increased net energy requirements for cows in the MUD treatment, there were no subsequent effects observed for steer BW, gain:feed, or response to glucose and ACTH during the growing phase.

Predictions for the Midwest U.S. indicate that both winter and spring temperatures and precipitation will increase. These climatic changes could result in muddier conditions during winter and spring in the Midwest. It has previously been demonstrated that a muddy environment increases the net energy requirements of mature cow's by approximately 3.9 Mcal/d. If cows are not provided this extra energy and are exposed to mud during late gestation, it is likely that this will cause an adverse environment for the conceptus that could result in compromised growth and metabolism later in life. This study evaluated the developmental programming effects after birth and into the growing phase with beef steers born to cows that were housed in a muddy environment during late gestation compared with steers born to cows that were housed in pens bedded with wood chips during late gestation. Based on the present results, the mature cows housed in the muddy conditions weighed approximately 37.4 kg less than cows housed in pens bedded with wood chips during late gestation, however, calf birth weight, postnatal growth, postnatal feed intake and gain:feed, and postnatal response to glucose and adrenocorticotropic hormone was not affected. This indicates that the mature cows were able to mobilize body stores and supplied the fetus with adequate nutrients during gestation without impairment of growth or postnatal response to glucose and adrenocorticotropic hormone.

Energy restriction and housing of pregnant beef heifers in mud decreases body weight and conceptus free live weight.

Average temperatures in the Midwest, USA are predicted to increase 2-9°C by the end of the century; resulting in muddy pastures for spring calving beef heifers as they enter late gestation. The objective of this study was to evaluate the effects of muddy conditions on heifer body weight (BW), body condition score (BCS), conceptus free live weight (CFLW), and fetal growth when heifers were energy restricted during late gestation. Eighteen Angus heifers (n = 9/treatment) were paired based on initial BW. One heifer from each BW pair was randomly allocated to either the mud (MUD) or control (CON) treatment on day 196 of gestation. Pens in the CON treatment were bedded with wood chips, while pens in the MUD treatment were filled with mud (average depth of 19.5 ±â€…7.9 cm). Heifers were housed individually and fed the same diet that consisted of a limit-fed total mixed ration from day 196 to 266 of gestation that was formulated to meet 66% of the net energy for maintenance, growth, and gestation requirements. Requirements and the amount of the diet offered were adjusted weekly, and heifers were weighed and sampled for blood metabolites weekly. Data were analyzed as a randomized complete block design with repeated measurements. There was a treatment × day of gestation interaction, such that heifers had similar BW, BCS, and CFLW on day 196 of gestation. By day 266 of gestation; however, heifers in the MUD treatment weighed 43.5 kg less (P < 0.01) and were 1.8 BCS units less (P < 0.01) than heifers in the CON treatment. This is further supported by the treatment × day effects we observed for back fat (BF) and rump fat (RF) thickness, such that the MUD heifers had less BF (P = 0.02) and RF (P < 0.01) by day 266 of gestation. There was a marginally significant difference for gestation length (P = 0.06), such that heifers in the MUD treatment calved approximately 3.1 days before the heifers in the CON treatment. Though heifers in the MUD treatment decreased their BW and CFLW during the treatment period, we did not observe a difference in calf birth weight (P = 0.34), calf plasma IgG concentration (P = 0.37), or calf weaning weight (P = 0.63). Despite heifers in the MUD treatment having greater BW, CFLW, and BCS losses compared with the heifers in the CON treatment, the heifers in the MUD treatment seemed to prioritize fetal growth, as they mobilized their body tissues to meet the energetic demands of pregnancy.

Short communication: A comparison between two glucose measurement methods in beef steers during a glucose tolerance test.

Glucose tolerance tests (GTT) are commonly performed in beef cattle to evaluate the glucose-insulin signaling pathway. Blood samples are obtained via a catheter and then transferred back to the laboratory for further analysis. A hand-held glucometer used chute-side can make performing GTT's and quantifying blood glucose concentration much easier and faster for research purposes. The purpose of this study was to evaluate the agreement between a hand-held electronic glucometer (Precision Xtra; Abbott Diabetes Care Inc., Mississauga, ON, Canada) for chute-side use in beef cattle compared with a colorimetric assay in the laboratory (Stanbio Glucose LiquiColor; Stanbio Laboratory, Boerne, TX, USA). A GTT was performed on 13 Simmental × Angus steers during the growing phase. Blood samples were obtained via a jugular catheter. Glucometer readings were taken immediately after blood was sampled from the jugular with no preservative, and laboratory measurements were conducted on plasma preserved with sodium fluoride. A paired t-test (P = 0.40), Pearson's correlation (P < 0.001; r = 0.95), Bland-Altman plot, and Lin's concordance correlation coefficient (LCCC = 0.90) were completed to evaluate the performance of the glucometer relative to the results from the laboratory assay. Based on the results, we conclude that the glucometer is an acceptable method for measuring blood glucose concentration in beef cattle under field conditions.

Beef cows housed in mud during late gestation have greater net energy requirements compared with cows housed on wood chip bedding.

Mud increases net energy requirements for cattle because mud and precipitation compromise the ability of the hair coat to insulate and maintain core body temperature of the cow. The increase in energy required for a gestating cow to compensate for a muddy environment is unknown. The objective of this study was to evaluate effects of muddy conditions on cow body weight (BW) and fetal growth during late gestation. Sixteen multiparous Angus cows (n = 8/treatment) were paired based on initial BW and one cow from each pair was randomly allocated to either the mud (MUD) or control (CON) treatment on day 213 of gestation. Pens in the CON group were bedded with wood chips, while pens in the MUD group were designed to create a muddy lot (average depth of 23.6 ± 5.8 cm). Cows were housed outdoors individually and fed the same diet that consisted of a limit-fed total mixed ration. Each pair was fed to meet energy and protein requirements for maintenance and gestation. From day 213 to 269 of gestation, cows were weighed and sampled for blood metabolites weekly. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). Though cows consumed the same amount of dry matter, cows in the MUD treatment weighed 37.4 kg less than cows in the CON treatment (P < 0.01) by day 269 of gestation. Cows in the MUD treatment decreased approximately half a body condition score (BCS), while cows in the CON treatment gained approximately 1 BCS during the treatment period (P < 0.01). There was no evidence of a treatment × day of gestation effect for 12th rib back fat (P = 0.85), rump fat (P = 0.48), total plasma protein concentrations (P = 0.85), or plasma 3-methylhistidine (P = 0.84); however, there was a marginally significant treatment × day of gestation effect for plasma non-esterified fatty acid concentration (P = 0.09). Despite differences in cow BW at the end of the treatment period, calf birth weight (P = 0.66) and calf total plasma protein (P = 0.27) were not different; however, the divergence in cow BW remained marginally significant at parturition (P = 0.06). These results indicate that mud increased net energy requirements for cows in the MUD treatment, as calf birth weight was not different but maternal BW was decreased compared with cows in the CON treatment.

Intranasal oxytocin treatment on the day of weaning does not decrease walking behavior or improve plasma metabolites in beef calves placed on pasture.

The purpose of this study was to evaluate the effect of intranasal oxytocin administered at abrupt weaning on weaning behaviors such as walking distance and time devoted to walking, calf body weight, and plasma non-esterified fatty acids (NEFAs), ß-hydroxybutyrate (ß-HB), and cortisol. Twenty Simmental × Angus heifer calves were randomly assigned to one of two treatments: intranasal oxytocin (OXT; n = 10) or intranasal saline (CON; n = 10). All calves were given the respective intranasal treatment on the day of weaning (day 0) and then placed on pasture together. Calves were weighed and a blood sample was obtained on days 0, 1, 7, and 14 postweaning. Blood samples were subsequently used to quantify plasma NEFA, ß-HB, and cortisol concentrations. All calves in both treatment groups were fitted with an individual global positioning system that recorded calf location every 10 s for a 16-h period on days 0, 7, and 14 to quantify and evaluate walking behaviors. There was no treatment × day effect for distance walked (P = 0.82), walking time (P = 0.80), non-walking time (P = 0.88), area utilization index (P = 0.84), calf body weight (P = 0.82), average daily gain (P = 0.54), NEFA (P = 0.22), or cortisol concentrations (P = 0.32). There was a tendency for a treatment × day effect observed for average walking speed (P = 0.09) and ß-HB (P = 0.10), such that calves in the CON treatment tended to have lesser average walking speeds on day 14 and tended to have greater ß-HB concentration after weaning. There was a treatment effect (P = 0.02) for NEFA concentrations, with the CON calves having a greater plasma NEFA concentration throughout the study compared with OXT calves. These data imply that OXT calves may have had differing metabolic responses immediately after weaning that could have altered the mobilization of NEFA, but this change was not substantial enough to impact body weights or walking behaviors.

Supplementation with eicosapentaenoic and docosahexaenoic acids in late gestation in ewes changes adipose tissue gene expression in the ewe and growth and plasma concentration of ghrelin in the offspring1.

Omega-3 long chain fatty acids have a positive impact on production. When consumed during late gestation, it might have fetal programming effects on the fetus, which will have lifelong impacts on development and production. The objectives of the present study were to evaluate the effect of increasing doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the diet of ewes in the last third of gestation on their body weight (BW), subcutaneous adipose tissue relative mRNA abundance of genes associated with adipose tissue metabolism, and growth performance and plasma metabolites and hormones of their offspring during the finishing phase. Ewes (n = 72) were blocked by BW and allotted to pens (8 per treatment) with 3 ewes per pen. Ewes were supplemented with an EPA and DHA source (Strata G113) at concentrations of 0, 1, or 2% of dry matter intake during the last 50 d of gestation. At lambing, all ewes were penned together and offered the same diet. After weaning at 60 d of age, lambs were blocked by BW and sex and fed for 56 d. All lambs were fed the same pellet diet (61.09% ground corn, 24.08% soy hulls, 11.09% soybean meal, 1.48% Ca salt of palm oil, and 2.26% mixed mineral vitamin), and were weighed every 14 d until the end of the trial. Blood samples were collected on the weight sampling days. Dry matter intake and refusals were weighed daily. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). Polynomial contrast (linear-L and quadratic-Q) was used for mean separation. There were no differences in ewe body condition score, milk production, milk fat, or milk protein, but there was a trend for increased (L, P = 0.06) lactose concentration, and also differences in DGAT1 (L, P = 0.04), Δ5-desaturase (Q, P = 0.06) and Δ6-desaturase (Q, P = 0.07), PPARα (Q, P = 0.03), ELOVL2 and 5 (Q, P < 0.07), FABP4 (Q, P = 0.04), FATP1 (Q, P = 0.06), leptin (Q, P = 0.02), and resistin (L, P = 0.05). Feeding pregnant ewes an increased amount of EPA and DHA in late gestation increased final BW (L, P = 0.01), ADG (L, P = 0.04; Q, P = 0.01), DMI (Q, P ≤ 0.01), plasma glucose concentration (L, P = 0.04), and trended to decrease ghrelin concentrations (L, P = 0.07) in offspring during the finishing period. Dam supplementation did not affect G:F, nor plasma NEFA concentration (P ≥ 0.53) of lambs. Therefore, increasing supplementation of EPA and DHA in pregnant ewes has an impact on offspring performance, increasing DMI, ADG, and BW.